Ventilator



Jan. 14, 1936.

W. J. MONTGOMERY VENTILATOR Filed 0013. 17, 1931 2 Sheets-Shet 1 I NVENTO/:

J. MONTGOMERY,

(9 WILLIAM ATTS.

Patented Jan. 14, 1936 UNITED STATES "2,021,647 vnn'rnla'ron William J. Montgomery,

signor to The Jeflrey Mann! Ohio, a corporation Application October 1'7, 1931, Serial No.

3 Claims. (01. 230-120) Columbus,

My invention relates to ventilators of the rotary fan type and one of its objects is to provide improved'and eflicient mechanism for directing the flow of air without contraction of suchflow, to make the full cross-sectional area of the air passageway effective. I

Another object of the invention is the provision of annular inlets and outlets respectively diverging to and converging from the plane of rotation 1 of the fan to render more effective the passageway. provided for air flow. A further object of the invention is the provision of a reversible rotary fan structure for a casing adapted to be connected to an air duct.

Another object of the invention is the provision of means at the central portion of arotary fan to prevent back flow which means shall also act to assist lnrendering more effective the crosssectional area of air flow through the fan.

A further object of the invention fan supporting mechanism with means to reduce interference with the flow of air past the same.

Another object of the invention is to select or use the most effective portions of aeroplane propeller blades and mount them for improved and eflicient operation in a ventilating fan.

Other objects of the invention will appear hereinafter, the'novel features and combinations being set forth in the appended claims. In the accompanying drawings,

- Fig. 1 is an elevational view of a ventilator embodying my im rovements;

Fig. 2 is a sectional elevation taken on the line 2-2 of Fig. '1 looking in the direction of the arrows, with a shaft coupling added;

. Fig. 3 is a view similar to Fig. 2 but reduced in size and with a pulley substituted for the shaft coupling; v

I Fig: 4 is an enlarged detail of a portion of Fig. 3; Fig. 5 is an elevational viewof one of theremovable aerofoil propeller blade sections;

Figs. 6A to 6H, inclusive, sections taken on the-lines A to 1-1, respectively, of Fig. 5, the shapes and contours of both sides of the aerofoil section shown in Fig. 5.

Fig. '7 is a sectional plan view of the lower portion of one of the hollow deflectors at the central portion of the fan structure shown in Figs. 1 and 3.

Fig. 8 is a sectional elevation taken on the'line 8- 8 of Fig. 1; and

Fig. 9 is afsectional elevation taken 9-9 of Fig. l.

As shown in Figs.

on the line 1 and 3 the fan casing I0 is mountedon the spaced-apart plates H, II which 5 are bolted .at 12, It to the concrete foundation .ing in the is to provide fan. structure they are show by means of Columbus, Ohio, as-

acturing Comm- V,

of Ohio I3. The casing III ma be provided with annular flanges ll, It at its periphery to facilitate mountarc-shaped recesses in the upright plates II, II and the securing of the casing ill to the mouth of a duct I! as indicated at l2. Such duct l5 may be of concrete l5 tunnel connected to the usual ventilating passageways in a coal mine, although I wish it to be understood that my improvements may have a general application.

To form the rotary fan I have found by experiment that the selection of approximately twothirds of the outer portions of aeroplane propeller blades extending from the outermost tips toward the axis of rotation and the mounting of such aerofoil sections l6, It as shown in the accompanying drawings, greatly increases the efflciency over that obtained in other ventilating fan structures in use for ventilation of coal mines. Preferably, each aerofoil section is shaped as shown in Figs. 5 and 6A to 61-1, inclusive, and mounted iorro'tation in the same plane, approximately symmetrical with respect to the casing I0. As shown in Figs. 6A to 6H, inclusive, the warping of the flatter side I! of each aerofoil section l6 varies from a little over 12 at the tip A to 33 at the section H near the hub extension It. Intermediate these extremes the angles with the horizontal lines vary as shown in Figs. 63 to 6G, inclusive, these being sectional views on the corresponding section lines of Fig. 5.

7 On that side I! of the aerofoil section It opposite the warped side I! the surface I! is provided with a distinct curvature as shown in Figs. 6A to BE, inclusive, so as to provide increased thickness of material to the right of the radial line 20, a short distance back from the leading edge 2| of the propeller blade. The trailing edge 22 is relatively thin. It should be understood that when the aerofoil sections are mounted in a rotated in the direction of the arrow 23 of Fig. 5-for greatest efficiency fan or in a blower.

sections it are secured by means 24. to the disc 25 the hub 26 of which is keyed to the shaft TI. The latter may be connected by the coupling 28- to the extension shaft 29. v

The'shaft 2'! is journaled in the bearings 30, 3t mounted on the channel cross-beams 32, 33 the ends of which are secured at 34, 35 to the casing to. Pipe pedestals 36, 31 have their lower ends secured at 3B, 39 to the lower portion of the casing l0 and their upper ends to the lower sides of the channels 32, 33 intermediate the in the form of a ends of the latter. As shown in Figs. 1 and 2 the vertical pedestals 36, 31 are directly under the journal bearings 38, 3|.

As shown at 48, 4| the journal bearings 38, 3| are detachable from the upper sides of the channels 32, 33 so that the entire fan structure in cluding all of the aerofoil sections shown in Fig. 1, is removable for repair or for reversal if desired. If the shaft 21 is rotated anti-clockwise as viewed in the direction of the arrow 58 of Fig. 2, so that the fan blades move in the direction of the arrow 42 of Fig. 1, the flow of air will be inward as indicated by the arrow 58 in Fig. 2, the fan then operating as a blower to force air into the duct l5.

In my former Patent No. 1,136,827, granted April 20, 1915, for an improvement in Fan blowers I have shown a central disc to prevent back currents of air. The present invention is a simplification of the construction shown in said patent and moreover the use of a single disc 25 in connection with removable propeller blades enables me to mount such disc so as to be symmetrical with respect tothe journal bearings 38, 3| whether the fan is'in one position or its reversed position. Furthermore, by the use of such a symmetrical disc the individual blades may be reversed in their positions on the disc 25 when the fan is to be changed from a suction fan to a blower or vice versa. The holes 68 in the hub end N3 of the blade section l6 enable the bolts 24 to secure the sections detachably to either side of the disc 25. The leading edges 2| should all be arranged so as to move in the desired direction of rotation. For instance, when the sections l6 are mounted as shown in Fig. 2 the direction of rotation is anti-clockwise as viewed in the direction of the arrow 58 whereas when the sections l6 are mounted on the opposite side of the disc 25 the leading edge 2| of each section should be reversed in position and adapted to move in a clockwise direction as viewed in the direction of the arrow 58.

After being individually reversed the blades l6 may be brought into the desired plane of rotation relative to the casing |8 by adjusting the hub 26 on the shaft 21. Suflicient clearances between the ends of the hub 26 and the bearings 38, 3| are provided to permit limited longitudinal movement of the hub along the key 59. The fan structure may be secured in adjusted position by means of the key set screws 6|, 6|.

I prefer to reverse the fan structure by detaching the inner framework from the casing l8 and sliding the hub 26 off the shaft 21; then replacing the same after reversal, on the key 59.

The inner framework comprises the channel am the pipe 36. The channel 32 is detachably secured to the casing l8 by means of the bolts 34' and 35 and the lower end of the pipe 36 is detachably secured to the casing 8 by means of bolts similar to those shown in Fig. 1 for detachably securing. the lower end of the pipe 31 to the casing l8.

The deflector 44 may remain in place on the inner framework while the latter is being moved inwardly to slide the inner bearing 38 oil the shaft 21. It should be understood that after this is done the fan structure can readily be reversed by sliding the same off the key 59 and off the shaft 21 and replacing such fan structure in reversed position on the shaft 21 and key 59. All of the supporting parts may then be restored to their positions shown in Figs. 1 and 2.

Covering the bearings 38, 3| are hollow shel s or deflectors 43, 44 each of about the diameter of the disc 25 and shaped so as to direct the flow of air along curved paths from the center of the deflector facing the current of air to the annular passageway in the plane of rotation of the fan. I The shape of each deflector is such that when the flow of air is against the same it reduces the tendency of the air current to con-. tract when in the plane of rotation of the fan. Whether the fan acts as a blower to force air into the duct l5 or as a suction fan to take air out of the duct |5 the flow of air through the fan casing 8 will be with maximum efficiency since the full cross-sectional area of the annular passageway is effective.

When the flow is into the duct l5 the inner deflector 44 prevents back flow of the air and when the flow is out of the duct |5 the outer deflector 43 acts to prevent back currents of air. It will thus be seen that the shells 43 and 44 each serves a double purpose in that each prevents back flow of air and moreover each acts when the flow of air is against it to eiflciently direct the flow of air into the plane of operation of the rotary fan.

As shown in Fig. 7, which is a sectional plan view of the lower half of the deflector 43, the latter is provided with a slot 44 to fit over the vertical pipe 31, and also with slots 45 and 46 for fitting over the channel cross-beam 33.

The lower portion of the shell 43 is provided with lateral extensions 41 and 48 which are adapted to flt over the cross-beam 33 as shown in Fig. 8 which is a section taken on the line 8-8 of Fig. 1 locking in the direction of the arrows. By means of screws 49 the lateral extensions 41, 48 may be detachably secured to the cross-beam 33. In a similar manner the deflector 44 may be detachably secured to the channel cross-beam 32.

It should be particularly noted that the upper. lower and forward sides of the extensions 41, 48 are curved as shown at 58, 5|, 52 in Fig. 8 so as to reduce interference with the flow of air into the fan casing. The ends of the screws 49 are arranged to be flush with the surfaces 58, 5|.

In co-operation with the curved surfaces of the deflectors 43 and 44 I have provided rounded or curved surfaces at the entry 54 and at the outlet 55 of the fan casing ID in order to make more effective the cross-sectional area of the annular passageway in which the fan blades rotate. The surfaces at 54, 55 are preferably so shaped as to, have a cross-sectional curvilinear path which in co-operationwith the cross-sectional curvilinear path afforded by the shells 43, 44 shall be in approximation of a Venturi duct. In this manner the annular inlet port converges to the plane of operation of the fan blades and the outlet port diverges from such plane to the duct I5. By providing such annular ports with the walls thus shaped actual contraction of the stream of air is prevented where such contraction would be most undesirable, that is, in the plane of rotation of the fan. In other words, the flow of air is so effectively directed and controlled that while passing through the casing it is acted upon with maximum efllciency by the fan blade sections.

By referring to Figs. 5 and 6 it will be understood that the efliciency of operation of the ventilator depends upon the shape of the aerofoil sections and the positions of the various surfaces at the cross-section of points illustrated in Fig. 62 Assuming the blade to be rotating in the direcfade; l'l l'la's the maximum pitch angle 'where the circle offrotation is the smallest and theminipitch angle (l2'l0") at the tipof the blade where'the circle of rotation is the greatest. The

airimpinging or propelling surface I! is warped or spiraled as shown in Fig. 6 in accordance with the increasing length of the circles through which the various radial portions of the blade travels. Furthermore, the outer portion of each blade is tapered toward the tip in the plane of rotation of the fan as viewed in Fig. 2 and is also tapered toward the tip relative to the direction of movement of the air through the ventilator as indicated by the arrow 58.

The leading edge portions of each blade is of decreasing thickness radially outward as shown in Fig. 6 to provide suction surfaces l9 of gradually decreasing pitch angles radially outward. It will also be seen that the various sections illustrated in Fig. 6 occupy gradually decreasing spaces between parallel planes at right angles to the section line 20.

The circles of rotation increase in length radially outward and therefore the speed of travel of the various sections illustrated in Fig. 6' increases gradually radially outward. The forces exerted by the impelling surface l1 and the suction surface iii are consequently distributed radially outward to produce a uniform pressure over the entire area of the opening through the ventilator to effect a uniform flow of air volume over such area in the direction of the arrow 58 parallel to the axis of rotation of the fan unit.

In other words the air impelling action and the air suction action each varies in accordance with the lengths of circles of rotationwith the result that in cooperation with the inletand outlet surfaces 54 and 55 and the central circular supporting structure, the blower action on the air will be uniformly distributed as to pressure and volume overthe entire annular area of the opening through the ventilator, thereby greatly increasing the efficiency of the ventilator.

By reason of the tapering of the el ngated aerofoil sections radially outward and t e distributlon of the impelling and suction surfaces I1 and I9, there is inherent in the rotary fan unit as determined by actual experiment a self-limitation feature in that when an electric motor is provided for normal operation under given conditions the fan head or resistance in the duct I5 may be increased or decreased within wide limits without overloading the motor. For instance if the ventilator is used to introduce air into the coal mine and too many doors are closed in the mine entries, the fan head may be increased to such an extent that there is a tendency to overload the motor in its effort to operate the fan unit-against the increase in pressure or resistance. However, by reason of the tapering of the blades as illustrated in Figs. 2 and 5, sufficient slip of the fan blades relative to the air acted on by such blades will prevent overloading of the motor. If the doors in the mine are all open to permit free flow of air, the tendency ofthe motor will be to be overloaded by the increased volume of air sent into the mine by the ventilator. But here again the self-limiting feature of the fan unit will also prevent overloading of the motor. Asmaller motor may therefore be used with the assurance that it will be of substantially constant horse power for a wide range of conditions which vary automatically and beyond the control of the operator of the ventilator.

In order to enable the air to freely flow past the supporting framework I have provided oval coverings 56, 51 for the channel 33 between the extensions 41, 48 and the channel ends 34,. 35. l

The surfaces of suchcoverings are preferably flush with the surfaces'50, 5l, 52 of the lateral extensions", 48. Pipes 36, 31 are preferred for the vertical pedestals for strength and to minimize air friction- In Figs. 3 and 4 I have shown a modification of the casing iii in that the faces 54' and 55' a are in cross-section to say, the inlet and the outlet ports are each in the .form of a frustum of a cone joined at their smaller diameters in the plane of rotation of the fan structure comprising the aerofoll sections IS.

The vertical pedestals 36f and 31 may be I- beams and no coverings provided for the channel cross-beams 82, 33. Furthermore in Fig. 3 the shells 43 and 44 of Fig. 2 are omitted and the shaft 21 is provided with a driving pulley 58 for connection by a belt to a distant motor out of the current of air produced by rotation of the on rectilinear lines. That is fan. Inthe form shown in Fig. 2 the shaft .29

may be connected to a distant driving motor.

Certain features of the invention herein disclosed are also disclosed and described in more detail in my applicationfor ventilators, Serial No. 689,293,-flled September 19, 1933.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claimsv hereto appended and I wish thereforenot to be restricted to the precise construction herein dis-' closed.

Having thus described and shown an embodiment of my invention what I desire to have secured by Letters Patent of the United States is:- What I claim is:

1. In a ventilator, the combination with 9. casing, of a rotary support having flat faces on opposite sides thereof, aerofoil propeller blades each having a relatively thick leading edge and a relatively thin trailing edge and each having splraled surfaces on opposite sides thereof to other in substantially the same plane relative to said casing.

2. In a ventilator, the combination of a casing having intake and outlet surfaces respectively converging and diverging, a rotary support having flat faces on opposite sides thereof, aerofoil propeller blades each having a relatively thick leading edge and a relatively thin trailing edge and, eaeh having splraled surfaces on opposite sides thereof to provide a graduation in the pitch angles radially outward on such opposite sides, and means for detachably securing said propeller blades on one side of said rotary support for ro tation with the latter in one direction and on the the propeller blades to rotate in one direction or I propeller blades to rotate in one direction or the r other side thereof for rotation with the latter in to said casing.

3. In a ventilator, the combination of a casing having intake and outlet surfaces respectively converging and diverging, a rotary support having flat faces on opposite sides thereof, aerofoil propeller blades each having a relatively thick leading edge and a relatively thin trailing edge and each having spiraled surfaces on opposite sides thereof to provide a graduation in the pitch angles radially outward on such opposite sides, and means for detachably securing said propeller blades on one side of said rotary support for rotation with the latter in one direction and on the other side thereof for rotation with the latter in the opposite direction, the mounting of said propeller blades being on the fiat surfaces of said rotary support and enabling the fan comprising 5 means comprising a pair' of stream lined casings, 10

one extending in each direction from said supporting means.

WILLIAM J. MONTGOMERY. 

